RE: Name lookup question

["Collins, Kevin [MindWorks]" <KCollins chevrontexaco com>]

Yes, getent is nice - too bad it isn't on all the platforms I support. I
think for linux that is best answer - I had forgotten about it!

Kevin  

-----Original Message-----
From: taroon-list-bounces redhat com
[mailto:taroon-list-bounces redhat com] On Behalf Of Ed Brown
Sent: Thursday, May 12, 2005 10:10 AM
To: Discussion of Red Hat Enterprise Linux 3 (Taroon)
Subject: RE: Name lookup question

On Thu, 2005-05-12 at 10:39, Collins, Kevin [MindWorks] wrote:
> Yes, that makes sense, I guess. The biggest issue I have is that I
don't
> have a good tool to see how the OS is resolving a certain name or IP
> address. 

This:

getent hosts <ip.or.hostname.to.lookup> 

I think is the best way to test the nsswitch path.  'Host' appears to go
straight to the dns libraries.

# strace -e trace=open getent hosts redhat.com
open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or
directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
open("/lib/tls/libc.so.6", O_RDONLY)    = 3
open("/etc/resolv.conf", O_RDONLY)      = 3
open("/etc/nsswitch.conf", O_RDONLY)    = 3
open("/etc/ld.so.cache", O_RDONLY)      = 3
open("/lib/libnss_files.so.2", O_RDONLY) = 3
open("/etc/host.conf", O_RDONLY)        = 3
open("/etc/hosts", O_RDONLY)            = 3
open("/etc/ld.so.cache", O_RDONLY)      = 3
open("/lib/libnss_dns.so.2", O_RDONLY)  = 3
open("/lib/libresolv.so.2", O_RDONLY)   = 3
open("/etc/hosts", O_RDONLY)            = 3
209.132.177.50  redhat.com


# strace -e trace=open host redhat.com
open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or
directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
open("/usr/lib/libdns.so.16", O_RDONLY) = 3
open("/usr/lib/libisc.so.7", O_RDONLY)  = 3
open("/lib/libcrypto.so.4", O_RDONLY)   = 3
open("/lib/libnsl.so.1", O_RDONLY)      = 3
open("/lib/tls/libpthread.so.0", O_RDONLY) = 3
open("/lib/tls/libc.so.6", O_RDONLY)    = 3
open("/usr/kerberos/lib/libgssapi_krb5.so.2", O_RDONLY) = 3
open("/usr/kerberos/lib/libkrb5.so.3", O_RDONLY) = 3
open("/usr/kerberos/lib/libcom_err.so.3", O_RDONLY) = 3
open("/usr/kerberos/lib/libk5crypto.so.3", O_RDONLY) = 3
open("/lib/libresolv.so.2", O_RDONLY)   = 3
open("/lib/libdl.so.2", O_RDONLY)       = 3
open("/usr/lib/libz.so.1", O_RDONLY)    = 3
open("/usr/share/locale/C/libdst.cat", O_RDONLY) = -1 ENOENT (No such
file or directory)
open("/usr/share/locale/C/LC_MESSAGES/libdst.cat", O_RDONLY) = -1 ENOENT
(No such file or directory)
open("/usr/share/locale/C/libdst.cat", O_RDONLY) = -1 ENOENT (No such
file or directory)
open("/usr/share/locale/C/LC_MESSAGES/libdst.cat", O_RDONLY) = -1 ENOENT
(No such file or directory)
open("/usr/share/locale/C/libisc.cat", O_RDONLY) = -1 ENOENT (No such
file or directory)
open("/usr/share/locale/C/LC_MESSAGES/libisc.cat", O_RDONLY) = -1 ENOENT
(No such file or directory)
open("/usr/share/locale/C/libisc.cat", O_RDONLY) = -1 ENOENT (No such
file or directory)
open("/usr/share/locale/C/LC_MESSAGES/libisc.cat", O_RDONLY) = -1 ENOENT
(No such file or directory)
open("/usr/share/locale/C/libdns.cat", O_RDONLY) = -1 ENOENT (No such
file or directory)
open("/usr/share/locale/C/LC_MESSAGES/libdns.cat", O_RDONLY) = -1 ENOENT
(No such file or directory)
open("/usr/share/locale/C/libdns.cat", O_RDONLY) = -1 ENOENT (No such
file or directory)
open("/usr/share/locale/C/LC_MESSAGES/libdns.cat", O_RDONLY) = -1 ENOENT
(No such file or directory)
open("/etc/resolv.conf", O_RDONLY)      = 5
redhat.com has address 209.132.177.50

-Ed

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